DAYUM !!!!
So I thought this power supply I put together was, well, probably kinda wimpy. Yeah, I hit it with a couple amps and it just had a tiny blip then back to flat 12VDC. But I figured if I hit it with more power it would probably explode in a flaming mass of LTSpice metal.
So I figured, "okay, just for grins let's hit it with some real power". So I did a simulation with applying 6 amps/72 watts to the 12VDC output. It probably wouldn't survive the initial dip.
And how did the power supply respond??
It replied "HA !!! I sneer and spit on your measly, wimpy 72 watts !!!"

DAMN, this thing is a MONSTER

A brief hiccup for 10mSec or so, then a nice smooth recovery back to a totally flat 12VDC. And Ith is still hanging below 2 volts after about 0.1 second.
I'll let it run for a while, but it appears like we have a winner. It looks like tuning the switching transformer is a key component in all of this, so now I have to figure out why it worked so well.